The present invention relates to a control device for holding the seat post of office chairs and the seat post is enclosed by a C-shaped sleeve with tapered inner periphery and the sleeve is received in a tapered hole of the base frame.
A conventional office chair includes a control device that controls the height of the seat and generally involves a hydraulic cylinder and the seat post is connected to the piston rod of the cylinder so that when the users operate the hydraulic cylinder, the seat post is lowered or raised by the movement of the piston rod. However, the cylinder is expensive and has a potential problem of leakage of the liquid in the cylinder. Besides, the number of parts composing the cylinder is large and every part has to be machined to have suitable holes. All of these make the office chair to have a high price and cannot be popular for most of the customers. In other words, there are no office chairs, in the market having adjustable height of the seat and sold at lower price.
The present invention intends to provide an office chair that has a control device for holding the seat post and the seat post is easily to be lowered or lifted.
In accordance with one aspect of the present invention, there is provided an office chair and comprises a frame having a tube with a tapered inner periphery and two holes are defined through the tube. A plurality of legs extend from the tube. A C-shaped sleeve is movably received in the tube and has a tapered outer periphery. The sleeve has a threaded inner periphery and a slit is defined longitudinally through the sleeve. Two notches are defined in the tapered outer periphery of the sleeve and two pins extend through the two holes in the tube and are engaged with the two notches. A seat post extends through the sleeve and has a threaded section which is engaged with the threaded inner periphery.
The primary object of the present invention is to provide an office chair wherein the seat post is firmly positioned when a load is applied on the seat post, and the seat post can be adjustable when lifting the seat post.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.